iOS 在被杀死/暂停时快速后台位置更新，数据丢失最少

Question

关于后台位置更新，我有几个问题要用swift语言问。

让我解释一下我在应用程序中做什么。我正在开发一款定期监控用户位置(就像你们所有人一样)并将其更新到服务器的应用程序，以便跟踪并保存用户的移动以供用户将来引用。

问题

1. 使用 startMonitoringSignificantLocationChanges 与 startUpdatingLocation 之间的区别是什么？

   1.1 如果我们使用 startUpdatingLocation 是否影响发布应用到 App Store？

2. 当应用被终止/暂停(用户强制关闭)时，位置管理器需要一些时间来重新启动来自 AppDelegate，这会导致一段时间内位置数据丢失。有什么可能的解决方案来克服这个问题吗？

   2.1 重新启动的时间差在30秒到将近1分钟，这不会触发位置更新，因此路线并不完美如图所示在图片

中

由于重新启动而未收到位置的应用程序输出，因此路线越过道路。

引用代码

import UIKit
import GoogleMaps

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, CLLocationManagerDelegate {

    var window: UIWindow?
    let DBName = "test"
    var logFile: FileUtils?
    var viewController:ViewController?

    var count = 0
    var appOpenCount = 0
    let totalPath = GMSMutablePath()
    var leaveCoordinates = 0
    var previousLocation: CLLocationCoordinate2D = CLLocationCoordinate2D(latitude: 0, longitude: 0)
    var locationManager: CLLocationManager?
    var significatLocationManager : CLLocationManager?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        // Override point for customization after application launch.
        GMSServices.provideAPIKey("*********************")
        logFile = FileUtils(fileName: "\(DBName).txt")

        logFile!.appendFile("\n\nlaunchOptions : \(launchOptions)")

        let defaults = NSUserDefaults.standardUserDefaults()
        count = defaults.integerForKey("Enabled")
        appOpenCount = defaults.integerForKey("appOpenCount")

        if(UIApplication.sharedApplication().backgroundRefreshStatus == UIBackgroundRefreshStatus.Available){
            logFile!.appendFile("\nYessss")
        } else {
            logFile!.appendFile("\nNooo")
        }

        appOpenCount += 1
        defaults.setValue(appOpenCount, forKey: "appOpenCount")
        defaults.synchronize()

        if count == 0 {
            count += 1
            defaults.setValue(count, forKey: "Enabled")
            defaults.synchronize()
            Util.copyFile(count)
        }

        if let launchOpt = launchOptions{
            if (launchOpt[UIApplicationLaunchOptionsLocationKey] != nil) {
                logFile!.appendFile("\nExecuted on : significatLocationManager")
                self.significatLocationManager = CLLocationManager()
                self.significatLocationManager?.desiredAccuracy = kCLLocationAccuracyBest
                self.significatLocationManager?.delegate = self
                self.significatLocationManager?.requestAlwaysAuthorization()
                if #available(iOS 9.0, *) {
                    self.significatLocationManager!.allowsBackgroundLocationUpdates = true
                }
                self.significatLocationManager?.startUpdatingLocation()
            }else{
                logFile!.appendFile("\nExecuted on : locationManager1")
                self.locationManager = CLLocationManager()
                self.locationManager?.desiredAccuracy = kCLLocationAccuracyBest
                self.locationManager?.delegate = self
                self.locationManager?.requestAlwaysAuthorization()
                if #available(iOS 9.0, *) {
                    self.locationManager!.allowsBackgroundLocationUpdates = true
                }
                self.locationManager?.startUpdatingLocation()
            }
        } else {
            logFile!.appendFile("\nExecuted on : locationManager2")
            self.locationManager = CLLocationManager()
            self.locationManager?.desiredAccuracy = kCLLocationAccuracyBest
            self.locationManager?.delegate = self
            self.locationManager?.requestAlwaysAuthorization()
            if #available(iOS 9.0, *) {
                self.locationManager!.allowsBackgroundLocationUpdates = true
            }
            self.locationManager?.startUpdatingLocation()
        }
        return true
    }

    func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]){
        let locationArray = locations as NSArray
        let newLocation = locationArray.lastObject as! CLLocation
        let coordinate = newLocation.coordinate

        let tempCoor = CLLocationCoordinate2D(latitude: coordinate.latitude, longitude: coordinate.longitude)
        let lat = tempCoor.latitude
        let lon = tempCoor.longitude
                insert(lat, lon: lon)
    }

    func applicationWillResignActive(application: UIApplication) {
        // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
        // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
    }

    func applicationDidEnterBackground(application: UIApplication) {
        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
        if self.significatLocationManager != nil {
            self.significatLocationManager?.startMonitoringSignificantLocationChanges()
        }else{
            self.locationManager?.startMonitoringSignificantLocationChanges()
        }
        logFile!.appendFile("\napplicationDidEnterBackground")
    }

    func applicationWillEnterForeground(application: UIApplication) {
        // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
    }

    func applicationDidBecomeActive(application: UIApplication) {
        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    }

    func applicationWillTerminate(application: UIApplication) {
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    }

    func insert(lat: Double, lon: Double){
        let locationInfo: LocationDetails = LocationDetails()
        locationInfo.latitude = lat
        locationInfo.longitude = lon
        locationInfo.time = NSDate()
        let db = "\(DBName)\(count).sqlite"
        ModelManager.getInstance(db).addLocationData(locationInfo)
    }
}

Answer 1

问题1

使用 startMonitoringSignificantLocationChanges 与 startUpdatingLocation 之间的区别是什么？

startUpdatingLocation 在第一次调用时更新位置，然后在超过距离过滤器值时更新位置。

它会在可用时使用 GPS，如果你连续使用它会耗尽你的电量/电池

讨论

This method returns immediately. Calling this method causes the location manager to obtain an initial location fix (which may take several seconds) and notify your delegate by calling its locationManager:didUpdateLocations: method. After that, the receiver generates update events primarily when the value in the distanceFilter property is exceeded. Updates may be delivered in other situations though. For example, the receiver may send another notification if the hardware gathers a more accurate location reading.

Calling this method several times in succession does not automatically result in new events being generated. Calling stopUpdatingLocation in between, however, does cause a new initial event to be sent the next time you call this method.

If you start this service and your application is suspended, the system stops the delivery of events until your application starts running again (either in the foreground or background). If your application is terminated, the delivery of new location events stops altogether. Therefore, if your application needs to receive location events while in the background, it must include the UIBackgroundModes key (with the location value) in its Info.plist file.

In addition to your delegate object implementing the locationManager:didUpdateLocations: method, it should also implement the locationManager:didFailWithError: method to respond to potential errors.

startMonitoringSignificantLocationChanges 当位置发生重大变化时。

它使用蜂窝或 wifi，当它工作时位置会改变或在特定时间间隔内被调用。

讨论

This method initiates the delivery of location events asynchronously, returning shortly after you call it. Location events are delivered to your delegate’s locationManager:didUpdateLocations: method. The first event to be delivered is usually the most recently cached location event (if any) but may be a newer event in some circumstances.

Obtaining a current location fix may take several additional seconds, so be sure to check the timestamps on the location events in your delegate method.

After returning a current location fix, the receiver generates update events only when a significant change in the user’s location is detected. For example, it might generate a new event when the device becomes associated with a different cell tower. It does not rely on the value in the distanceFilter property to generate events. Calling this method several times in succession does not automatically result in new events being generated. Calling stopMonitoringSignificantLocationChanges in between, however, does cause a new initial event to be sent the next time you call this method.

If you start this service and your application is subsequently terminated, the system automatically relaunches the application into the background if a new event arrives. In such a case, the options dictionary passed to the locationManager:didUpdateLocations: method of your application delegate contains the key UIApplicationLaunchOptionsLocationKey to indicate that your application was launched because of a location event. Upon relaunch, you must still configure a location manager object and call this method to continue receiving location events. When you restart location services, the current event is delivered to your delegate immediately. In addition, the location property of your location manager object is populated with the most recent location object even before you start location services.

注意:

Apps can expect a notification as soon as the device moves 500 meters or more from its previous notification. It should not expect notifications more frequently than once every five minutes. If the device is able to retrieve data from the network, the location manager is much more likely to deliver notifications in a timely manner.

出于不同的目的，我取自 here

问题2

如果我们使用 startUpdatingLocation 是否影响发布应用程序到 App Store？

One of the possible reasons for 2.16 rejection is the absence of GPS battery warning in your app description on the app meta in iTunesConnect - "The continued use of GPS may decrease battery life" or something like that.

有关 this 的更多信息

问题3

当应用被终止/暂停(用户强制关闭)时，需要一些时间来重新启动 AppDelegate 的位置管理器这会导致在一段时间内丢失位置数据。任何可能的解决方案来克服这个问题

NO, we Can't Over Come, reason the memory newly Initiated.